Don’t ask her next time, it’s very rude of her to suggest specific expensive items.
She could have given you general suggestions without naming specific high price items.
Then it would be up to you how much you fork out.

Just buy what you think is reasonable and ignore her.

I’ve previously had the same where I’ve asked In-laws and been suggested several ideas of which some are frankly too extravagant.
I just buy what I want now ask don’t ask anymore.

It’s especially annoying when you know you get rubbish from the ones who suddenly have a craving for cashmere…

Cheeky! We are more in the £25-35 range for my nieces and nephews, but often this is one toy gift around £25 and then a book.  I think you can be blunt (since they have been with the requests) and reply what your budget is. You could offer to give them £xx cash each so they can save towards those items, if they have their hearts set on them. 

Totally agree with the above posters! My children’s (same age), uncles, aunts, godparents etc, wouldn’t go above probably about £30.. the presents you mention are what I myself would spend on one of my children on a joint birthday/Christmas gift in one! The eldest son birthday is Christmas Eve so we often get larger gifts to cover both.

I would love you to be my aunty   I think taking the proverbial. I'd suggest saying love the ideas but might need to get slightly less expensive models or something similar?

Can anyone please give me a steer on whether or not I am being mean. Trying to get ahead for Christmas and asked my SIL to have a think about ideas for my nephew and niece who are 10 and 8. I'm a bit stunned by the cost of the presents that she has suggested.  One of the presents, a scalextric set 
is nudging £90 and the other, an ice watch just over £80. I am quite taken aback. I would normally be looking to spend around £50 on Christmas presents for family.
We are more comfortably off than my husband's family but regardless I feel it is rude to ask for such expensive things and not really in the spirit of the whole thing. Just can't work out if I am being mean or if she is trying to take advantage.